The present invention relates to a transmission for a working vehicle equipped with a bucket implement or a backhoe implement, and particularly to a transmission for a working vehicle known as a body flexion type vehicle comprising a front frame including front wheels and a rear frame including rear wheels, the front and rear frames being interconnected to be pivotable relative to each other on a substantially vertical axis. This type of vehicle is steerable by pivoting the front frame relative to the rear frame.
Generally, the body flexion type working vehicle has an engine and a transmission mounted on the rear frame, with the transmission disposed forwardly of the engine. The transmission includes a planetary change speed gear assembly constituting an upper, change speed portion and an output shaft constituting a lower, output portion. In the known construction, the planetary change speed gear assembly has an input gear thereof disposed at or adjacent a rear end of the change speed portion and an output gear thereof disposed at or adjacent a front end of the change speed portion, the output gear being operatively connected to the output shaft.
Therefore, where the output shaft includes a coupling device at a front end thereof for connection to a propeller shaft for driving the front wheels included in the front frame, it is inevitable that the coupling device is positioned forwardly of a front wall of a case housing the change speed portion since the output gear for transmitting power to the output shaft is disposed at or adjacent the front end of the change speed portion. This results in a great maximum angle of deviation of the propeller shaft with respect to the output shaft at times of steering the vehicle by pivoting the front frame relative to the rear frame, which is contrary to good efficiency of power transmission to the front wheels.
In a further example of known transmission adapted for use in working vehicles not limited to the body flexion type working vehicle, the planetary change speed gear assembly comprises a first and a second planetary gear devices having respective carriers interlocked to be rotatable in unison. The first planetary gear device includes a sun gear operatively connected to the input shaft, and the second planetary gear device includes a sun gear operatively connected to an intermediate output shaft which in turn is operatively connected to the output shaft. This known transmission having such a construction is capable of effecting multistep speed changes. The input shaft and the intermediate output shaft of this known transmission extend longitudinally of the vehicle in an end-to-end arrangement.
Therefore, the first and second planetary gear devices in combination have a great length in the fore and aft direction of the vehicle. It is also necessary to provide intermediate bearings at a position where the input shaft and the intermediate output shaft are opposed end to end. Thus the known transmission has the disadvantage of being large and cumbersome.